A Microporous Hydrogen Bonded Organic Framework for Highly Selective Separation of Carbon Dioxide over Acetylene

Abstract

The separation of acetylene (C2H2) from carbon dioxide (CO2) is a very important but challenging task due to their similar molecular dimensions and physical properties. In terms of porous adsorbents for this separation, the CO2‐selective porous materials are superior to the C2H2‐selective ones because of the cost‐ and energy‐efficiency but have been rarely achieved. Herein we report our unexpected discovery of the first hydrogen bonded organic framework (HOF) constructed from a simple organic linker 2,4,6‐tri(1H‐pyrazol‐4‐yl)pyridine (PYTPZ) (termed as HOF‐FJU‐88) as the highly CO2‐selective porous material. HOF‐FJU‐88 is a two‐dimensional HOF with a pore pocket of about 7.6 Å. The activated HOF‐FJU‐88 takes up a high amount of CO2 (59.6 cm³ g⁻¹) at ambient conditions with the record IAST selectivity of 1894. Its high performance for the CO2/C2H2 separation has been further confirmed through breakthrough experiments, in‐situdiffuse reflectance infrared spectroscopy and molecular simulations.

A Microporous Hydrogen‐Bonded Organic Framework Based on Hydrogen‐Bonding Tetramers for Efficient Xe/Kr Separation

“…Miljanić group reported three isostructural pyrazolyl porous HOFs with large BET surface areas (903–1821 cm 2 g −1 ) and they all established triplets of hydrogen bonds between pyrazoles [8b,c] . Our group recently also reported a pyrazolyl HOF (HOF‐FJU‐88) which exhibits a significant preferential CO 2 adsorption over C 2 H 2 and hydrogen‐bonding trimers also found in the structures [13] . Notably, we observed that a trigonal molecular shape is critical for the formation of hydrogen‐bonding trimers.…”

Deciphering Mechanisms of CO2-Selective Recognition over Acetylene within Porous Materials

“…HOF-FJU-88, a two-dimensional HOF featuring a pore size of approximately 7.6 Å, where bilayers exhibit slipped AA stacking facilitated by weak π•••π interactions between pyrazole units. 64 This configuration allows for the selective adsorption of CO 2 molecules, which are stabilized within the 2D layers by multiple weak hydrogen bonds to three neighboring hydrogen atoms from pyrazole rings. The adsorption capacity is enhanced through the alignment of electrostatic potential.…”

Subtle Structural Variations within Solvent-Free D–A-Type Organic Crystals for Tuning Emission Wavelength up to 47 nm Shift

“…Organic crystals including hydrogen-bonded organic frameworks (HOFs) are auspicious multifunctional materials, − with versatile properties such as functionalized channels, tuneable pore sizes, solution processability, and ease of regeneration, ,− making them suitable for diverse applications including gas adsorption, − proton conduction, , catalysis, , biology, and fluorescence sensing. − A notable characteristic lies in their potential design flexibility, enabling the integration of different organic luminescent chromophores within their structural framework. Given the sensitivity of luminescence as a visual signal, organic crystals with distinctive luminescent characteristics may find applications in chemical sensing, detection, molecular recognition, barcode identification, and other research areas. − …”